1. Field of the Invention
The present invention relates to seals in general, and specifically to compression seals. More specifically, the present invention relates to wellhead assemblies, and to an improved system, method and apparatus for forming a metal seal between inner and outer wellhead members. Ease of assembly and dismantling for reuse are desirable attributes.
2. Description of Related Art
A variety of metallic seal configurations exist. Many metallic seals are commonly held under compression between two opposed flanges of the elements being sealed to each other. Many examples of metallic seals are of an annular configuration, having a convoluted radial section which permits the seal to act as a spring and maintain engagement with the flanges despite changes or variations in the flange separation. Some of these seals have an S-like section, while others have a section similar to the Greek capital letter sigma (Σ), with diverging base and top portions. Other seals are formed with additional convolutions.
Non-provisional U.S. patent application Ser. No. 11/610,220, filed Dec. 13, 2006, by Hailing, entitled, “SEAL,” and incorporated by reference herein, teaches the use of metal seals and, in particular, the use of frustro-conical rings with a rounded-trapezoidal seal cross-section having two parallel sides, for large wellheads, usually provided with hydraulically-actuated systems for assembling and dismantling piping joints therein. For smaller wellheads, such functions must be performed by screw-threaded devices or smaller, radially-disposed hydraulic tools.
Further descriptions of the prior art are cited and illustrated by Jennings, published in U.S. Publication No. 2008/0265517 A1, entitled, “SYSTEM, METHOD, AND APPARATUS FOR ENERGIZABLE METAL SEALS IN WELL HEADS.”